scholarly journals Energetics of super cyclone ‘GONU’ and very severe cyclonic storm ‘SIDR’

MAUSAM ◽  
2021 ◽  
Vol 65 (1) ◽  
pp. 37-48
Author(s):  
Sunitha DeviS ◽  
Somnath Dutta ◽  
K Prasad
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Meridional Circulation ◽  
North Indian Ocean ◽  
Moist Static Energy ◽  
Cyclonic Storm ◽  
Available Potential Energy ◽  
Mean Meridional Circulation ◽  
Static Energy ◽  
Severe Cyclonic Storm

This paper discusses the energetics aspects of two tropical cyclones formed over the north Indian Ocean during 2007, viz., the Super Cyclonic Storm (GONU) and the Very Severe Cyclonic Storm (SIDR). From the analysis of  various energetics terms such as the  Eddy Available Potential Energy (AE), Zonal Available Potential Energy (AZ), Zonal Kinetic Energy (KZ), Eddy Kinetic Energy (KE) and their generation and inter-conversions i.e., G(AE), G(AZ), C(AE, KE), C(AZ, KZ), C(KZ, KE) and C(AZ, AE)  have  been computed on day to day basis during the periods of their intensifications over the domain 5° N to 25° N, 55° E to 75° E in respect of ‘GONU’ and 5° N to 25° N, 77° E to 97° E for ‘SIDR’. Besides the above, the area averaged value of s (Sigma), the vertically averaged Moist Static Energy (MSE), has also been computed on each day. Day-to-day evolution of these parameters is mapped and described. Some of the distinguishing features in the energetic of these two intense vortices which formed in entirely different climatological settings have been brought out. It is noticed that in the case of ‘GONU’, though both barotropic and baroclinic energy conversions have taken place during the life cycle, the intensification phase is characterized by an enhancement in AE, KE and vertically integrated Moist Static Energy. Enhancement in AE can be attributed to the generation of AE, which may again be attributed to the asymmetric latent heat of condensation associated with the asymmetric rainfall in the cyclone field. Enhancement in KE may be attributed to the enhancement in both barotropic and baroclinic conversion into KE. Though most of these observations made for ‘GONU’ are found to be attributable to ‘SIDR’ as well, the intensification of ‘SIDR’ appears to have more similarity to that of a typical growing mid-latitude baroclinic wave. In this case, the enhancement in AE, could also be attributed to positive C(AZ,AE), which is mainly due to interaction with mid-latitude baroclinic westerly wave. The energetics analysis also indicates that GONU had helped in the enhancement of seasonal mean meridional circulation where as the SIDR had inhibited the enhancement of seasonal mean meridional circulation.  

scholarly journals Dr. Yanai’s Contributions to the Discovery and Science of the MJO

2016 ◽  
Vol 56 ◽  
pp. 4.1-4.18 ◽  
Author(s):  
Eric D. Maloney ◽  
Chidong Zhang
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Energy Budget ◽  
Momentum Transport ◽  
Energy Budgets ◽  
Equatorial Waves ◽  
Madden Julian Oscillation ◽  
Moist Static Energy ◽  
Moist Static Energy Budget ◽  
Static Energy

Abstract This chapter reviews Professor Michio Yanai’s contributions to the discovery and science of the Madden–Julian oscillation (MJO). Professor Yanai’s work on equatorial waves played an inspirational role in the MJO discovery by Roland Madden and Paul Julian. Professor Yanai also made direct and important contributions to MJO research. These research contributions include work on the vertically integrated moist static energy budget, cumulus momentum transport, eddy available potential energy and eddy kinetic energy budgets, and tropical–extratropical interactions. Finally, Professor Yanai left a legacy through his students, who continue to push the bounds of MJO research.

Study of the Mechanisms of Vortex Variability in the Lofoten Basin Based on the Energy Analysis

2021 ◽  
Vol 37 (3) ◽  
Author(s):  
V. S. Travkin ◽  
◽  
T. V. Belonenko ◽  
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Baroclinic Instability ◽  
Positive Trend ◽  
Barotropic Instability ◽  
Available Potential Energy ◽  
Conversion Rates ◽  
Order Of Magnitude ◽  
The Mean ◽  
Mean Kinetic Energy

Purpose. The Lofoten Basin is one of the most energetic zones of the World Ocean characterized by high activity of mesoscale eddies. The study is aimed at analyzing different components of general energy in the basin, namely the mean kinetic and vortex kinetic energy calculated using the integral of the volume of available potential and kinetic energy of the Lofoten Vortex, as well as variability of these characteristics. Methods and Results. GLORYS12V1 reanalysis data for the period 2010–2018 were used. The mean kinetic energy and the eddy kinetic one were analyzed; and as for the Lofoten Vortex, its volume available potential and kinetic energy were studied. The mesoscale activity of eddies in winter is higher than in summer. Evolution of the available potential energy and kinetic energy of the Lofoten Vortex up to the 1000 m horizon was studied. It is shown that the vortex available potential energy exceeds the kinetic one by an order of magnitude, and there is a positive trend with the coefficient 0,23⋅1015 J/year. It was found that in the Lofoten Basin, the intermediate layer from 600 to 900 m made the largest contribution to the potential energy, whereas the 0–400 m layer – to kinetic energy. The conversion rates of the mean kinetic energy into the vortex kinetic one and the mean available potential energy into the vortex available potential one (barotropic and baroclinic instability) were analyzed. It is shown that the first type of transformation dominates in summer, while the second one is characterized by its increase in winter. Conclusions. The vertical profile shows that the kinetic energy of eddies in winter is higher than in summer. The available potential energy of a vortex is by an order of magnitude greater than the kinetic energy. An increase in the available potential energy is confirmed by a significant positive trend and by a decrease in the vortex Burger number. The graphs of the barotropic instability conversion rate demonstrate the multidirectional flows in the vortex zone with the dipole structure observed in a winter period, and the tripole one – in summer. The barotropic instability highest intensity is observed in summer. The baroclinic instability is characterized by intensification of the regime in winter that is associated with weakening of stratification in this period owing to winter convection.

scholarly journals MSE Minus CAPE is the True Conserved Variable for an Adiabatically Lifted Parcel

2015 ◽  
Vol 72 (9) ◽  
pp. 3639-3646 ◽  
Author(s):  
David M. Romps
Keyword(s):  
Potential Energy ◽  
Thermodynamic Equilibrium ◽  
Convective Available Potential Energy ◽  
Potential Temperature ◽  
Equivalent Potential Temperature ◽  
Moist Static Energy ◽  
Neutral Buoyancy ◽  
Equivalent Potential ◽  
Nonhydrostatic Pressure ◽  
Static Energy

Abstract For an adiabatic parcel convecting up or down through the atmosphere, it is often assumed that its moist static energy (MSE) is conserved. Here, it is shown that the true conserved variable for this process is MSE minus convective available potential energy (CAPE) calculated as the integral of buoyancy from the parcel’s height to its level of neutral buoyancy and that this variable is conserved even when accounting for full moist thermodynamics and nonhydrostatic pressure forces. In the calculation of a dry convecting parcel, conservation of MSE minus CAPE gives the same answer as conservation of entropy and potential temperature, while the use of MSE alone can generate large errors. For a moist parcel, entropy and equivalent potential temperature give the same answer as MSE minus CAPE only if the parcel ascends in thermodynamic equilibrium. If the parcel ascends with a nonisothermal mixed-phase stage, these methods can give significantly different answers for the parcel buoyancy because MSE minus CAPE is conserved, while entropy and equivalent potential temperature are not.

Linking surface enthalpy fluxes to the forces driving the secondary circulation: towards a causal theory of tropical cyclone intensification

2020 ◽  
Author(s):  
Remi Tailleux ◽  
Bethan Harris ◽  
Christopher Holloway ◽  
Pier-Luigi Vidale
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Power Input ◽  
Causal Theory ◽  
Density Field ◽  
Secondary Circulation ◽  
Reference State ◽  
Available Potential Energy ◽  
Available Energy ◽  
Surface Enthalpy

<p>While it is well accepted that tropical cyclones (TCs) derive their energy from surface enthalpy fluxes over the ocean, there is still little understanding of the precise causes and effects by which the latter ends up as TC vortex kinetic energy. For example, Potential Intensity (PI) theory, which has been so far the main framework for predicting TC intensities, assumes a balance between the Carnot power input and the kinetic energy dissipated by surface friction, but says nothing of the detailed physical processes linking the two. A similar criticism pertains to the WISHE (Wind Induced Surface Heat Exchange) theory. To achieve a causal theory of TC intensification, the main difficulty is in linking the power input to kinetic energy production, rather than kinetic energy dissipation. Because kinetic energy is produced at the expense of available potential energy (APE), APE theory is arguably the most promising candidate framework for achieving a causal theory of TC intensification. However, in its current form, the usefulness of APE theory appears to be limited in a number of ways because of its reliance on a notional reference state of rest. First, APE production associated with standard reference states (i.e., horizontally averaged density field, density field of initial sounding, adiabatically sorted states, ...) is usually found to systematically overestimate the kinetic energy actually produced in ideal TC simulations, similarly as the Carnot theory of heat engines; moreover, the standard APE is only connected to vertical buoyancy forces, but says nothing of the radial forces required to drive the secondary circulation. To address these shortcomings, this work presents a new theory of available energy (AE) that is based on the use of an axisymmetric vortex reference state in gradient wind balance. This theory possesses the following advantages over previous frameworks:</p><p> </p><ul><li>The available energy (AE) thus constructed possesses both a mechanical and thermodynamic component. The thermodynamic component is analogous to the well-known Slantwise Convective Available Potential Energy (SCAPE), whereas the mechanical component is proportional to the anomalous azimuthal kinetic energy;</li> <li>The rate of AE production by surface enthalpy fluxes is found to be a very accurate predictor of the amount of potential energy actually converted into kinetic energy in idealised TC simulations based on the Rotunno and Emanuel (1986) axisymmetric model, although a few exceptions are found for cold SSTs;</li> <li>In addition to the expected thermodynamic efficiencies, the production term for AE also involves mechanical efficiencies predicting the fraction of the sinks/sources of angular momentum creating/destroying AE;</li> <li>The AE is related to a generalised buoyancy/inertial force that has both vertical and horizontal components; at low levels, such a generalised force has radially inward and vertically upward components, as required to drive the expected secondary circulation.</li> </ul><p>The new theory, therefore, appears to possess all the ingredients to form the basis for a causal theory of TC intensification.</p>

scholarly journals Energy of Midlatitude Transient Eddies in Idealized Simulations of Changed Climates

2008 ◽  
Vol 21 (22) ◽  
pp. 5797-5806 ◽  
Author(s):  
Paul A. O’Gorman ◽  
Tapio Schneider
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Radiative Forcing ◽  
General Circulation ◽  
Thermal Structure ◽  
Circulation Model ◽  
Static Stability ◽  
Eddy Kinetic Energy ◽  
Available Potential Energy ◽  
Wide Range

Abstract As the climate changes, changes in static stability, meridional temperature gradients, and availability of moisture for latent heat release may exert competing effects on the energy of midlatitude transient eddies. This paper examines how the eddy kinetic energy in midlatitude baroclinic zones responds to changes in radiative forcing in simulations with an idealized moist general circulation model. In a series of simulations in which the optical thickness of the longwave absorber is varied over a wide range, the eddy kinetic energy has a maximum for a climate with mean temperature similar to that of present-day earth, with significantly smaller values both for warmer and for colder climates. In a series of simulations in which the meridional insolation gradient is varied, the eddy kinetic energy increases monotonically with insolation gradient. In both series of simulations, the eddy kinetic energy scales approximately linearly with the dry mean available potential energy averaged over the baroclinic zones. Changes in eddy kinetic energy can therefore be related to the changes in the atmospheric thermal structure that affect the mean available potential energy.

On the Decadal Variability of the Eddy Kinetic Energy in the Kuroshio Extension

2017 ◽  
Vol 47 (5) ◽  
pp. 1169-1187 ◽  
Author(s):  
Yang Yang ◽  
X. San Liang ◽  
Bo Qiu ◽  
Shuiming Chen
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Decadal Variability ◽  
Kuroshio Extension ◽  
Baroclinic Instability ◽  
Eddy Kinetic Energy ◽  
Time Varying ◽  
Barotropic Instability ◽  
Available Potential Energy ◽  
Decadal Modulation

AbstractPrevious studies have found that the decadal variability of eddy kinetic energy (EKE) in the upstream Kuroshio Extension is negatively correlated with the jet strength, which seems counterintuitive at first glance because linear stability analysis usually suggests that a stronger jet would favor baroclinic instability and thus lead to stronger eddy activities. Using a time-varying energetics diagnostic methodology, namely, the localized multiscale energy and vorticity analysis (MS-EVA), and the MS-EVA-based nonlinear instability theory, this study investigates the physical mechanism responsible for such variations with the state estimate from the Estimating the Circulation and Climate of the Ocean (ECCO), Phase II. For the first time, it is found that the decadal modulation of EKE is mainly controlled by the barotropic instability of the background flow. During the high-EKE state, violent meanderings efficiently induce strong barotropic energy transfer from mean kinetic energy (MKE) to EKE despite the rather weak jet strength. The reverse is true in the low-EKE state. Although the enhanced meander in the high-EKE state also transfers a significant portion of energy from mean available potential energy (MAPE) to eddy available potential energy (EAPE) through baroclinic instability, the EAPE is not efficiently converted to EKE as the two processes are not well correlated at low frequencies revealed in the time-varying energetics. The decadal modulation of barotropic instability is found to be in pace with the North Pacific Gyre Oscillation but with a time lag of approximately 2 years.

scholarly journals A Detailed Normal-Mode Energetics of the General Circulation of the Atmosphere

2012 ◽  
Vol 69 (9) ◽  
pp. 2718-2732 ◽  
Author(s):  
C. A. F. Marques ◽  
J. M. Castanheira
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Normal Mode ◽  
General Circulation ◽  
Department Of Energy ◽  
Japan Meteorological Agency ◽  
Available Potential Energy ◽  
Conversion Rates ◽  
Zonal Wavenumber ◽  
New Formulation

Abstract An energetics formulation is here introduced that enables an explicit evaluation for the conversion rates between available potential energy and kinetic energy, the nonlinear interactions of both energy forms, and their generation and dissipation rates, in both the zonal wavenumber and vertical mode domains. The conversion rates between available potential energy and kinetic energy are further decomposed into the contributions by the rotational (Rossby) and divergent (gravity) components of the circulation field. The computed energy terms allow one to formulate a detailed energy cycle describing the flow of energy among the zonal mean and eddy components, and also among the barotropic and baroclinic components. This new energetics formulation is a development of the 3D normal-mode energetics scheme. The new formulation is applied on an assessment of the energetics of winter (December–February) circulation in the 40-yr ECMWF Re-Analysis (ERA-40), the 25-yr Japan Meteorological Agency Reanalysis (JRA-25), and the NCEP–Department of Energy Reanalysis 2 (NCEP-R2) datasets.

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